Understanding MPLS OAM capabilities to troubleshoot MPLS Networks Mukhtiar A. Shaikh (
[email protected]) Moiz Moizuddin (
[email protected]) 1 Agenda • MPLS Overview • Existing Ping/Trace Capabilities • LSP Ping/Trace –Theory of Operation –MPLS Echo Packet –Configuration and Troubleshooting Using LSP Ping/Trace •LSP Ping •LSP Trace –AToM VCCV • Summary 222 MPLS OAM Overview • Converged network implies a wide range of applications and OAM needs • IP Based Tools A flexible set of tools LSP Ping / Traceroute End-End OAM Attachment VC OAM’s MPLS OAM Attachment VC OAM’s Ingress Egress LSP Created by LDP and/or RSVP-TE CE PE PE CE PWE3 or VPN Label 333 Agenda • MPLS Overview • Existing Ping/Trace Capabilities • LSP Ping/Trace –Theory of Operation –MPLS Echo Packet –Configuration and Troubleshooting Using LSP Ping/Trace •LSP Ping •LSP Trace –AToM VCCV • Summary 444 IP Ping • PING makes use of the Internet Control Message Protocol (ICMP) protocol • Ping message of 2 types type=8: ICMP echo request messages type=0: ICMP echo reply message • Optional data field is used to store the time at which the ICMP echo request message has been send • The Round Trip Time (RTT) 555 IP Traceroute • Traceroute makes use of the Internet Control Message Protocol (ICMP) protocol and TTL field on the IP header • Traceroute is sent in a UDP packet encapsulated on an IP packet • TTL-field of an IP datagram is processed by each hop in two possible ways If a hop holds IP-datagram for more than one second, it decrements the TTL-field of that IP datagram by the number